1) Field of the Invention
The present invention relates generally to cooling systems, and more specifically to a fan control for controlling speed and direction of an electric radiator fan or similar cooling device.
2) Related Art
Off-road vehicles typically include electric fans to cool a radiator through which engine coolant circulates. Harsh environmental conditions result in build-up of debris on the radiator, and fan reversing systems are available to briefly reverse the fan direction periodically to clean the radiator or fan filter screen of accumulated debris. Such systems often have analog timers to control fan reversal, but achieving the long time delays requires several timers and is expensive.
Additional fan controls including two or more thermostats are often provided to achieve low speed fan operation until the coolant temperature reaches a threshold temperature and higher speed operation when the temperature is above threshold. Such varying fan speed operation increases efficiency, reduces noise and reduces the engine, battery and alternator loads until after the engine has reached the normal operating speed. The additional thermostat or thermostats necessary for the multi-speed fan operation add cost and complexity to the system. In some systems, the fan will automatically start when cranking the engine if the coolant temperature is above a preselected temperature thereby increasing drain on the battery during starting and adding load on the engine and alternator before the engine reaches normal operating speed.